U.S. CPA & Advisory Firm
Independent audit. Strategic advisory. Global perspective.
JCK Yoonsung LLP serves domestic and multinational businesses with audit, tax, accounting advisory, transaction advisory, and financial advisory services. We bring Big Four technical experience, practical execution, and deep cross-border expertise.
Who We Are
A partner-led firm for companies that expect more than compliance.
JCK Yoonsung LLP is headquartered in Southern California and provides professional services to U.S. businesses, private companies, multinational groups, and growing organizations across a wide range of industries.
While we are recognized for our Korea–U.S. cross-border expertise, our practice extends well beyond Korean companies. We serve businesses across the United States and global markets that need responsive, technically sound, and practical accounting and advisory support.
Core Services
Integrated support across the business lifecycle.
Audit & Assurance
Financial statement audits, reviews, group reporting package audits, internal controls, and SOX/K-SOX support.
02Accounting Advisory
US GAAP, IFRS, technical accounting, financial reporting, accounting policies, and readiness support.
03Tax Services
Federal, state, international tax compliance and planning for domestic and multinational businesses.
04Transaction Advisory
Due diligence, quality of earnings, valuation support, and deal execution support.
05Financial Advisory
CFO advisory, process improvement, internal controls, FP&A, and operational finance support.
Why JCK
Global capability. Boutique responsiveness.
Our professionals combine Big Four experience in the United States and Korea with the responsiveness of a focused advisory firm.
Partner-led service
Senior professionals remain directly involved throughout the engagement.
Technical depth
Experience across US GAAP, IFRS, K-IFRS, SEC/PCAOB environments, and complex reporting needs.
Practical execution
Advice designed to be implemented by management, not just documented.
Cross-border fluency
Strong communication across U.S. teams, global headquarters, and group auditors.
Industries
Experience across dynamic sectors.
Let’s Talk
Looking for audit, tax, or advisory support?
Connect with our team to discuss your business needs.
Contact JCK Yoonsung